This course is designed to provide a full overview of computer networking. We’ll cover everything from the fundamentals of modern networking technologies and protocols to an overview of the cloud to practical applications and network troubleshooting.
By the end of this course, you’ll be able to:
● describe computer networks in terms of a five-layer model
● understand all of the standard protocols involved with TCP/IP communications
● grasp powerful network troubleshooting tools and techniques
● learn network services like DNS and DHCP that help make computer networks run
● understand cloud computing, everything as a service, and cloud storage

Avis

AM

what an amazing course, so much information and yet so easy to understand, would recommend going over a few of the videos and supplemental reading a few times, take the time needed, it'll be worth it.

AA

Mar 26, 2020

Filled StarFilled StarFilled StarFilled StarFilled Star

Great course. It is great for beginners and for people that may have forgotten a thing or two. The way it was taught makes it so much better than reading man pages or something else as dry and boring.

À partir de la leçon

The Transport and Application Layers

In the third week of this course, we'll explore the transport and application layers. By the end of this module, you'll be able to describe TCP ports and sockets, identify the different components of a TCP header, show the difference between connection-oriented and connectionless protocols, and explain how TCP is used to ensure data integrity.

Enseigné par

Google

Transcription

A socket is the instantiation of an endpoint in a potential TCP connection. An instantiation is the actual implementation of something defined elsewhere. TCP sockets require actual programs to instantiate them. You can contrast this with a port which is more of a virtual descriptive thing. In other words, you can send traffic to any port you want, but you're only going to get a response if a program has opened a socket on that port. TCP sockets can exist in lots of states. And being able to understand what those mean will help you troubleshoot network connectivity issues as an IT support specialist. We'll cover the most common ones here. LISTEN. Listen means that a TCP socket is ready and listening for incoming connections. You'd see this on the server side only. SYN_SENT. This means that a synchronization request has been sent, but the connection hasn't been established yet. You'd see this on the client side only. SYN_RECEIVED. This means that a socket previously in a listener state, has received a synchronization request and sent a SYN_ACK back. But it hasn't received the final ACK from the client yet. You'd see this on the server side only. ESTABLISHED. This means that the TCP connection is in working order, and both sides are free to send each other data. You'd see this state on both the client and server sides of the connection. This will be true of all the following socket states, too. So keep that in mind. FIN_WAIT. This means that a FIN has been sent, but the corresponding ACK from the other end hasn't been received yet. CLOSE_WAIT. This means that the connection has been closed at the TCP layer, but that the application that opened the socket hasn't released its hold on the socket yet. CLOSED. This means that the connection has been fully terminated, and that no further communication is possible. There are other TCP socket states that exist. Additionally, socket states and their names, can vary from operating system to operating system. That's because they exist outside of the scope of the definition of TCP itself. TCP, as a protocol, is universal in how it's used since every device speaking to TCP protocol has to do this in the exact same way for communications to be successful. Choosing how to describe the states of a socket at the operating system level isn't quite as universal. When troubleshooting issues at the TCP layer, make sure you check out the exact socket state definitions for the systems you're working with.